Cover lifting-and swinging mechanism for a tiltable furnace

ABSTRACT

A cover lifting- and swinging mechanism for a tiltable crucible smelting or oven-type furnace wherein the cover is first caused to lift and then swing to an open position for completely emptying the furnace pot after the furnace charge has been drawn off in the usual manner through a pouring spout. The combined lifting and swinging motions imparted to the cover are effected and controlled by means of a hydraulic cylinder secured at the side of the tiltable furnace structure. The piston component of the cylinder is connected to a cylindrical housing having a swing arm that is secured to the cover and the housing is provided with a cam groove associated with a stationary guide roll so as to exercise positive control over the cover and piston movement.

United States Patent [191 Huwyler et al.

[ Aug. 14, 1973 Inventors: Ernst Huwyler, Wettingen; Heinrich Wenzel,Baden, both of Switzerland Aktlengesellschaft Brown, Boveri & Cie,Baden, Switzerland Filed: Feb. 1, 1972 Appl. No.: 222,562

[73] Assignee:

[30] Foreign Application Priority Data Feb. 5, 1971 Switzerland 1698/71References Cited UNITED STATES PATENTS 11/1950 Thys 263/33 A X 3,684,2618/1972 Wynne 263/33 A Primary Examiner-John J. Camby Attorney-Ralph E.Parker et a1.

[ ABSTRACT A cover liftingand swinging mechanism for a tiltable cruciblesmelting or oven-type furnace wherein the cover is first caused to liftand then swing to an open position for completely emptying the furnacepot after the fumace charge has been drawn OK in the usual mannerthrough a pouring spout. The combined lifting and swinging motionsimparted to the cover are effected and controlled by means of ahydraulic cylinder secured at the side of the tiltable furnacestructure. The piston component of the cylinder is connected to acylindrical housing having a swing arm that is secured to the cover andthe housing is provided with a cam groove associated with a stationaryguide-roll so as to exercise positive control over the cover and pistonmovement.

2 Claims, 3 Drawing Figures COVER LllFTllNG-AND SWlNGllNG MECHANISM FORA TllLTABLE FURNACE The present invention relates to an improved coverlifting-and swinging mechanism for a crucible smelting or oven-typefurnace, whereby the cover is operated through a swinging arm by meansof a hydraulic cylinder which is fastened to the furnace.

The covers of known cover liftingand swinging systems for cruciblesmelting furnaces are first lifted vertically and then swiveled by meansof a cam groove which is engaged by a fixed guide roll, whereby the camgroove is connected with the piston of the hydraulic cylinder. However,such devices wherein the cover of the furnace is lifted and swunglaterally for the charging, the removal of slag or specimen, aredisadvantageous because they offer no safeguard against a selfactingopening of the cover and a forward shifting of the hydraulic cylinerpiston whenever the furnace is tilted to its extreme position, forexample in excess of 90. Such tilting of the furnace is a generalpractice of all foundries in order to empty completely the furnace pot,its inner surface not being smooth.

Furthermore, most foundries employ for economic reasons a suspensiontrolley, consisting of a track and traveling crane with cable line,whereby the melting pot can be moved across the smelting furnace whilethe distance to the furnace is not variable, being set on the basis ofthe mean value of the pouring jet at the various tilting positions ofthe furnace. Due to the above discussed self-acting shifting of thehydraulic piston and the opening of the cover, the cover will, bynecessity, come in contact with the cable line which supports themelting pot. For this reason there is the possibility that molten metalwill excape from the melting pot and endanger the service personnel.Furthermore, the collision between furnace cover and cable line cancause portions of the ceramic lining of the furnace cover to drop downbecause the lining will become red-hot during the smelting operations,thus becoming impactsensitive. I

The self-acting forward shifting of the hydraulic cylinder piston willlead to an increase in the cylinder displacement but this space can notbe filled with pressure fluid because the supply line to the cylinder isblocked; a vacuum can not be generated either because conditions willnot permit this, with the result that air will flow from outside betweenpiston and seal into the bore of the hydraulic cylinder. An air cushionwill thus form within the hydraulic system which can be removed only bya time-consuming and work-interfering bleeding of the hydraulic cylinderafter each tilting of the furnace.

it is the primary object of the present invention to provide an improvedcover liftingand swinging mechanism for a crucible smelting or oven-typefurnace whereby the cover is operated through a swinging arm by means ofa hydraulic cylinder fastened to the furnace, and whereby anyself-acting opening of the cover will be prevented during thefurnace-tilting operation, i.e. at the extreme position of the furnacefor discharge of the contents.

In accordance with the invention the cover is retained against openingby a movable arrangement at the upper end of the hydraulic cylindercomprising a cylindrical housing which is fixedly connected on one sideto the swinging arm and detachably connected on the other side to thepiston of the hydraulic cylinder,

the outside of said housing being provided with a cam groove which isengaged by a roll that is fastened at the furnace or at a platformconnected to the furnace, whereby the upper portion of the cam groove,which actuates the lifting of the cover, inclines slightly relative tothe housing axis, gradually merging into a cam portion which inclinessteeply relative to the housing axis, the latter cam portion serving togenerate the swinging motion of the cover.

A preferred embodiment of the invention is described below in detail andis illustrated by the accompanying drawings wherein:

FIG. 1 shows a crucible smelting furnace in side view, also depicting bymeans of dot and dash lines the furnace in tilting position (angle oftilt approx.

FIG. 2 provides a top view of the tilted furnace; and

FIG. 3 shows a diagram of the housing, with the cam groove illustratedat an enlarged scale.

With reference now to the drawings, a tiltable crucible smelting furnace11 is provided with a platform 2, and the melting pot is closed offagainst the outside by means of a heat-blocking cover 5. This cover 5 isfastened to a supporting arm 6, the arm being welded to a cylindricalhousing 7 which is arranged movably at the upper end of a hydrauliccylinder 8 and which is detachably connected with the piston of thehydraulic cylinder. At the outer surface of the housing 7 there isprovided a cam groove 9, engaged by a roll 10 which is arranged at thefurnace platform 2. This roll is balanced by a block 11, provided at theplatform 2 which supports the cover 5. The furnace is also equipped witha pouring lip 12 and a hydraulic cylinder 15 which generates the tiltingmotion of the furnace. Numeral 16 denotes a pan which is suspended froma line 17.

3 Shows tlxths uppetpqrtiqnqf th c graav's', arranged at the housing 7and provided with a very small angle of inclination, approximately 3 to5, relative to the axis X)( of the housing 7, this portion of the grooveserving for the lifting of the cover 5. This upper groove portion mergesgradually into the lower groove portion which has a steep angle ofinclination, for example at least 45, relative to the housing axis X-X,this portion of the groove being used to generate the swiveling motionof the furnace cover 5.

The cover liftingand swinging mechanism operates in the followingmanner:

For the purpose of pouring off its contents, the furnace l is tilted bythe hydraulic cylinder 15 in known manner, and the molten metal thenflows in accordance with the angle of tilt from the furnace 1 over thepouring lip 12 into the pan to which is suspended from the line 17. Thelatter is connected in known manner with a, not illustrated, travelingcrane which moves along a track across the furnace. Normally, thefurnace cover 5 will be closed during this tilting operation.

Whenever the furnace needs to be emptied completely, the angle of tiltmust be at least close to 100 from the vertical, as depicted in FIG. 1,and it will then be necessary to prevent the cover 5 to open by itselfin this specific tilting position through gravitational force as willhappen in case of the above discussed conventional cover liftingandswing'ng devices. This is accomplished by the mechanism proposed inaccordance with the invention characterized in that due to the smallangle of inclination throughout the upper portion of the cam groove 9 arise in the center of gravity M, of the cover is forcibly accomplished,and the wedging effect, so generated, will thus prevent a forwardsliding of cylinder 7 or cover respectively in the direction of arrow P(see FIG. 1). In order to open the cover 5, it is necessary to actuatethe, not illustrated, controls of the hydraulic cylinder 8, with theresult that first the center of gravity of the cover will shift by anangle a to M the cover is thus lifted up and will then perform a lateralswing through an additional movement by the angle (a B) to point M Ifthe cover is to be opened toward the rear, its center of gravity ismoved hydraulically first by an angle a from M to M and then by an angleB to M' In this case the lower portion of the cam groove 9 must beprovided with an inclination which is opposite to the direction depictedin FIG. 3.

The above described mechanism has the substantial advantage that thefurnace cover will be kept closed in a positive manner when the furnaceis in its discharge position and will never unseat itself during thisposition. The housing with this specific cam groove, locking the furnacecover in its closed position, can also be used in connection withpresently existing furnaces; it is only necessary to provide thehydraulic cylinder which is already present and causes the lifting andswinging of the cover with such a housing 7, and to connect the housingwith the arm supporting the cover and with the piston of the hydrauliccylinder.

The cam groove and the roll can be interchanged as to their positionwithout altering the essence of the invention. Likewise, the hydrauliccylinder which operates the furnace cover can be replaced by a pneumaticlifting device.

We claim:

1. A combined cover lifting and swinging mechanism for a tiltablecrucible smelting or oven type furnace comprising a hydraulic cylindersecured to the tiltable furnace structure, said hydraulic cylinder beinglocated at the side of and parallel with the furnace structure so thatthe piston thereof extends vertically upward when said furnace structureoccupies a vertical position, a movable cylindrical housing connected tothe piston of said hydraulic cylinder and with its longitudinal axisparallel to said piston, a swingable arm rigidly connected at theopposite ends thereof to the furnace cover and cylindrical housingrespectively, the outer side of said cylindrical housing being providedwith a cam groove engaged by a roll secured to the tiltable furnacestructure, said cam groove including an upper portion having a slightinclination to the longitudinal axis of said cylindrical housing whichserves to impart a lifting movement to said arm and cover from the mouthof the furnace when the piston of said hydraulic cylinder is initiallyactuated, said upper portion of said cam groove merging with a lowerportion having a steep inclination relative to the longitudinal axis ofsaid cylindrical housing and which serves to thereafter impart aswinging movement to said lifted arm and cover away from the furnacemouth as said piston is further actuated.

2. A combined lifting and swinging mechanism as defined in claim 1 for atiltable crucible smelting or oven type furnace wherein said upperportion of said cam groove has an inclination of from 3 to 5 and saidlower portion of said cam groove has an inclination of approximately 45.

* k k i

1. A combined cover lifting and swinging mechanism for a tiltablecrucible smelting or oven type furnace comprising a hydraulic cylindersecured to the tiltable furnace structure, said hydraulic cylinder beinglocated at the side of and parallel with the furnace structure so thatthe piston thereof extends vertically upward when said furnace structureoccupies a vertical position, a movable cylindrical housing connected tothe piston of said hydraulic cylinder and with its longitudinal axisparallel to said piston, a swingable arm rigidly connected at theopposite ends thereof to the furnace cover and cylindrical housingrespectively, the outer side of said cylindrical housing being providedwith a cam groove engaged by a roll secured to the tiltable furnacestructure, said cam groove including an upper portion having a slightinclination to the longitudinal axis of said cylindrical housing whichserves to impart a lifting movement to said arm and cover from the mouthof the furnace when the piston of said hydraulic cylinder is initiallyactuated, said upper portion of said cam groove merging with a lowerportion having a steep inclination relative to the longitudinal axis ofsaid cylindrical housing and which serves to thereafter impart aswinging movement to said lifted arm and cover away from the furnacemouth as said piston is further actuated.
 2. A combined lifting andswinging mechanism as defined in claim 1 for a tiltable cruciblesmelting or oven type furnace wherein said upper portion of said camgroove has an inclination of from 3* to 5* and said lower portion ofsaid cam groove has an inclination of approximately 45*.